O3 is dangerous until it reacts with itself to form O2 or reacts with on chemicals to form other compounds.
My statement was based on findings that looked into the byproducts of ozone reacting with nicotine
http://newscenter.lbl.gov/2010/08/16/ozone-and-nicotine-a-bad-combination-for-asthma/
Are you saying it is harmless? Because if you truly knew about the mere basics about ozone, it is well know that humans must stay away from ozone until it turns into oxygen gas or reacts with other chemicals. You would also have called it smog and and wrote a few paragraphs about the consequences of breathing that.
Also, because it is O3, it is highly reactive molecule that damages whatever can take that third oxygen molecule and become the more stable O2.
And perhaps you think I am fabricating this information too. So here is my advice. Buy an ozone generator, turn it on the max, and lock yourself in that room and take wonderfully deep breaths of it in the name of science to test if it truly is harmful or harmless.